login
A216656
Number of n-digit 6th powers.
2
2, 1, 1, 1, 2, 3, 5, 7, 10, 15, 22, 31, 47, 69, 101, 148, 217, 318, 468, 687, 1008, 1479, 2171, 3187, 4678, 6867, 10078, 14793, 21714, 31870, 46780, 68664, 100784, 147931, 217134, 318707, 467800, 686635, 1007843, 1479311, 2171332, 3187079, 4677993, 6866354
OFFSET
1,1
COMMENTS
a(6*k+1) + a(6*k+2) + a(6*k+3) + a(6*k+4) + a(6*k+5) + a(6*k+6) = 9*10^k for k >= 1. - Robert Israel, Jul 22 2018
LINKS
EXAMPLE
a(1) = 2: 0, 1.
a(2) = 1: 64.
a(3) = 1: 729.
a(4) = 1: 4096.
a(5) = 2: 15625, 46656.
a(6) = 3: 117649, 262144, 531441.
a(7) = 5: 1000000, 1771561, 2985984, 4826809, 7529536.
a(8) = 7: 11390625, 16777216, 24137569, 34012224, 47045881, 64000000, 85766121.
MAPLE
r:= proc(n, k) local b; b:= iroot(n, k); b+`if`(b^k<n, 1, 0) end:
a:= n-> r(10^n, 6) -r(10^(n-1), 6) +`if`(n=1, 1, 0):
seq(a(n), n=1..50);
CROSSREFS
Column k=6 of A216653.
Sequence in context: A134132 A308121 A030424 * A353435 A295679 A287214
KEYWORD
nonn,base
AUTHOR
Alois P. Heinz, Sep 12 2012
STATUS
approved